You’d think this would be like peanut butter and chocolate, two great things that taste even greater when mashed together. But I can’t think of a single zombie apocalypse movie that truly works.

The biggest such film–WORLD WAR Z–went splat, despite the star power of Brad Pitt and a big budget. Why?

I’ve pondered this, downed a pot of coffee and consulted the oracle.

Here’s the deal.

In a horror movie, everybody dies

Not because the screenwriter and director are sadistic. The whole point of a horror movie is society getting punished for its sins by the monster, who’s actually the hero.

That’s why Freddy, Jason and all the other horror monsters never truly get killed off.

Slasher movies show teenagers breaking the rules–shoplifting, getting drunk, having premarital sex, lying to their parents about it all–and getting punished by the boogeyman for their sins.

Another big branch of horror movies is about man playing God–inventing super-smart sharks with lasers, creating hybrid genetic experiments that go wrong, or sewing together body parts from the grave and using lightning to reanimate the thing. Then those creations rise up to punish the scientists for their arrogance.

This is why horror movies can fail. If the teenagers or scientists actually win in the end, the movie confuses the message. You might start out rooting for the teeny boppers or mad scientists, but in the end, you’re supposed to see the monsters as agents of rough justice.

Same thing with a zombie movie.

NIGHT OF THE LIVING DEAD is actually about racism.

DAWN OF THE DEAD is about consumerism, which is why it’s set in a mall.

Monster in the House is a great story and a dangerous one for zombies

There’s a primal story that screenwriter Blake Snyder identifies as Monster in the House, where there’s a monster in an enclosed space and either it’s gonna kill you or you’re gonna kill it.

JAWS, ALIEN and FATAL ATTRACTION are all Monster in the House stories.

There’s a big difference between these stories and a true horror movie. The ending is completely opposite.

The shark dies in the end of JAWS, as does the alien and the obsessed, discarded mistress played by Glenn Close.

NIGHT OF THE LIVING DEAD and DAWN OF THE DEAD feature the same enclosed space problem, because it’s good storytelling to put characters in a cage with your monster. But they stay true to the message and let the monsters win, punishing society for our sins.

In an apocalyptic movie, tons of people die–but the story ends with hope

The storytelling bones of a good apocalyptic movie are completely different than a horror story.

Civilization goes buh-bye, and the fun of an apocalyptic movie is seeing how that happens and what replaces the status quo.

Also, you get to loot the hardware store and the mall. Who doesn’t like to see that on film? Always a good time.

The message of an apocalypse film, though, is that lots of people die because they make bad, selfish choices, while the few heroes who survive make good, unselfish choices.

It just doesn’t work to mix a true zombie movie, where everybody dies as punishment for society’s sins, with an apocalyptic film, with its message of survival if you make the right choices.

So: back to the movie, WORLD WAR Z, which is a confused beast.

If you read the novel–which you should–it’s not a horror story, where everybody gets nom-nommed by the living dead. It’s a true zombie apocalypse story that can work, with the end showing the undead almost destroying the world. They’re only beaten when society makes painful, fundamental changes to work together and win the war.

Hope and survival. That’s the right way to thread the needle and tell a zombie apocalypse story that works. Give us that, Hollywood–Brad Pitt is optional.